Heat oil in a 10.5-inch skillet that has a lid over medium-high heat. Add sausage, breaking it up with a spoon as it browns, about 5-6 minutes. Add the onion and continue to cook until vegetables have softened, about 5 minutes. Stir in the red pepper flakes, oregano, Italian seasoning, garlic powder and stir until the meat mixture is fully coated.
Stir in water, tomato sauce and pasta. Reduce heat, cover and let cook, stirring occasionally, until pasta is tender, about 15-20 minutes. Cook time may vary depending on brand and type of pasta, so check for doneness often starting at the 15 minute mark.
Turn off the heat. Add the peas and one cup of the cheese and gently stir to combine. Season to taste with sea salt, top with remaining cheese and parsley, then serve.